At least 25% of jail inmates in large cities are untreated, intravenous drug-abusing street addicts, who at release are at high risk of reverting to IV drug use, AIDS-related drug and sexual practices, and drug-related criminality. Additional inmates are drug-dependent youthful offenders who only recently began IV drug use or who are cocaine abusers at risk of progressing to IV drug use. Until now only heroin detoxification has been available in some jails. An innovative jail-based, multi-modality drug treatment program began in 1987 within New York City's centralized jail complex at Rikers Island. The Key Extended Entry Program (KEEP) consists of in-jail men's and women's methadone maintenance units for heroin-addicted inmates; an in- jail drug free residence using therapeutic community principles for heroin or cocaine-abusing youthful offenders; and dedicated slots in community drug treatment programs for released offenders. This is the first introduction of methodone treatment into a jail setting. The study will evaluate the outcomes of KEEP, which is entirely New York City- and State-funded. The study will also demonstrate and evaluate a new, complementary service, Intensive Transition Services (ITS), designed to ensure continuity of treatment for KEEP particpants as they move from in-jail to community drug treatment programs. The study will use a controlled, pre-/post-tests experimental design. The subjects will be 520 drug-dependent jail inmates (260 adult males, 130 adult females and 130 adolescents males) assigned to interventions as follows: KEEP with ITS (120 adult methadone, 40 adolescent drug-free); KEEP only (120 adult methadone, 40 adolescent drug- free); Control (150 adult heroin detox, 50 adolescent controls). Data will be obtained at baseline and at a 6-month, post-release follow-up. Outcomes measured will be: entry rate into community drug abuse treatment and length of stay in treatment; changes in IV drug-using and sexual behaviors related to the risks of contracting or transmitting HIV; changes in illicit drug use in general; changes in drug-related criminality; rearrest rates and reincarceration rates; and chagnes in social productivity. If effective, the KEEP/ITS model is suitable for replication in large- cityjail systems around the country.